This invention relates generally to inspecting piping and, more particularly, to assemblies for inspecting piping, such as core spray piping, in nuclear reactors.
Nuclear reactors have many piping systems, and such piping systems are utilized, for example, to deliver feedwater to the reactor pressure vessel (RPV) and to deliver steam from the RPV to a power generator. Numerous pipes also typically are located within the RPV and sometimes are located in crowded spaces with many other pipes and other reactor equipment.
Over the life of the reactor, the piping systems are inspected to verify their integrity. For example, in accordance with NCR IandE Bulletin No. 70-13, issued May 12, 1980, core spray spargers and associated piping is visually inspected at every refueling outage. Based on such inspections, the piping systems may be modified, upgraded, repaired or replaced.
To inspect pipes within the RPV, ropes and poles typically are utilized for manual manipulation of simple tools or manual delivery of dedicated automated tools. More specifically, and during reactor shut down, an operator typically stands on a bridge positioned over the open RPV and using ropes and poles, which may extend more than thirty (30) feet below the bridge into the RPV, the operator positions cameras used to visually inspect the RPV piping. After visually inspecting the RPV piping, the operator conducts a supplemental ultrasonic examination (UT) to more thoroughly examine the piping and to verify the extent of any cracks identified visually. Both the ability to perform and the quality of such inspections greatly depends on the dexterity of the operator.
Due to the amount of piping to be inspected during reactor shut down, performing visual inspection and UT can be time consuming. It is desirable, of course, to limit the time required to perform repairs and inspections in the RPV since the reactor must be shut down to perform such tasks. Reducing the amount of time required to perform such inspections and repairs also would facilitate reducing the operator radiation exposure per task.
Performing visual inspection and UT also typically require extensive use of the bridge, which inhibits the ability to perform other inspections and repairs of RPV components. Particularly, many RPV inspections and repairs require an operator to manipulate tools from the bridge, and the amount of activity on the bridge generally is limited. Therefore, while the piping inspections are being conducted, other repairs and inspections cannot be performed.
It would be desirable to provided an automated piping inspection assembly particularly suitable for use in nuclear reactor applications which is easy to install and controllable for performing high quality piping inspections. It also would be desirable to provide such an inspection assembly which may be operated from a remote location other than the bridge to facilitate reducing reactor shut-down time.
These and other objects may be attained by an automated inspection assembly which includes a remotely operated vehicle (ROV) coupled to a mounting subassembly and a scanning subassembly controllable by a computerized motion control system. In one embodiment, the mounting subassembly includes a clamp configured to be mounted to selected pipes within the RPV, and the scanning subassembly is movably coupled to the mounting subassembly. The scanning subassembly includes a scanning head configured to perform an ultrasound inspection of the piping. The scanning head is configured to scan at least a portion of the circumference of the pipe to be inspected, and the scanning head includes a substantially xe2x80x9cUxe2x80x9d shaped transducer support assembly, and transducers are coupled to the ends of the transducer support assembly legs.
In operation, the remotely operated vehicle is controlled to transport the mounting and scanning subassemblies to the pipe to be inspected, and the mounting subassembly is mounted to the pipe. The scanning head is positioned proximate the portion of the pipe to be inspected so that the pipe extends through the legs of the transducer support assembly. The transducer support assembly is then rotated about the pipe to inspect the integrity of the pipe.
The above described automated inspection assembly is particularly suitable for use in nuclear reactor applications and is easy to install and controllable for forming high quality piping inspections. The assembly also may be operated from a remote location other than the bridge.